There are several ‘optional’ or ‘choice required’ steps during assembly of the PCBv3 MegaSquirt units, how are the DIYAutoTune ECU’s configured?

MegaSquirt-I EMS’s are setup by default as a fuel only EFI controller running though they are running the current stable release of the MS1/Extra firmware. These are configured to be triggered from the (-) negative terminal of the coil by default. It is fairly easy to convert them to be triggered from a Hall/Optical/Points trigger if you prefer. Here are the steps to take:

Cut out C12 and C30. Don’t jumper them or anything, just clip the leads and leave them out. (Assembly steps 50h and 50d)

Jumper D1. You can remove the diode first, but you don’t have to. It’s easier to just solder a little lead shorting both of it’s legs together.

MegaSquirt-II EMS’s are by default configured for fuel and ignition control running the current stable release of the MS2/Extra firmware. These are configured to be triggered from a Hall/Optical/Points trigger by default.

MegaSquirt-III EMS’s are by default configured for fuel and ignition control running the current stable release of the MS3 firmware. These are configured to be triggered from a Hall/Optical/Points crank trigger by default, and with the MS3X board added also support a similar Cam sensor input allowing sequential fuel injection.